Mess with globals

Related issue #1582

If your test messes with globals, a reasonable expectation is that you will clean up after yourself. This is not impossible in the case of process.stdout.write() or console.log(). In fact, it's pretty easy.

var expect = require('chai').expect;

describe('my nice test', function() {
  var write, log, output = '';

  // restore process.stdout.write() and console.log() to their previous glory
  var cleanup = function() {
    process.stdout.write = write;
    console.log = log;
    output = "";
  };

  beforeEach(function() {
    // store these functions to restore later because we are messing with them
    write = process.stdout.write;
    log = console.log;

    // our stub will concatenate any output to a string
    process.stdout.write = console.log = function(s) {
      output += s;
    };
  });

  // restore after each test
  afterEach(cleanup);

  it('should suppress all output if a non-AssertionError was thrown', function() {
    process.stdout.write('foo');
    console.log('bar');
    // uncomment below line to suppress output, which is bad
    // expect(output).to.equal(foobar);
    expect(output).to.equal('foobar');
  });

  it('should not suppress any output', function() {
    try {
      process.stdout.write('foo');
      console.log('bar');
      // uncomment below line to just throw an AssertionError
      // expect(output).to.equal('barfoo');
      expect(output).to.equal(foobar); // ReferenceError
    } catch (e) {
      cleanup();
      throw e;
    }
  });
});